Data terminal for use with TDMA processing repeater

ABSTRACT

The present invention relates to data terminals for use in a TDMA communication system which provides the individual data terminals with synchronization error measurements and other commands. Each individual data terminal is capable of transmitting a narrowband coarse synchronization signal in response to a system command, thereby permitting rapid initial synchronization to be achieved. The disclosed data terminals transmit data in burst fashion at one uplink bandwidth, and receive downlink data at a second, narrower bandwidth.

United States Patent 11 1 Schlosser et al.

Apr. 22, 1975 DATA TERMINAL FOR USE WITH TDMA PROCESSING REPEATER Inventors: Leslie H. Schlosser, Los Angeles;

Frank J. Moreno. Torrance. both of Calif.

Hughes Aircraft Company, Culver City. Calif.

Filed: Nov. 24, I972 Appl. N0.: 309,325

Assignee:

U.S. Cl. l79/l5 BS; 325/4 Int. Cl. H04] 3/06 Field of Search 325/4; l79/l5 BV. l5 BA l79/l5 85.15 BW References Cited UNITED STATES PATENTS Blasbalg 179/15 BV lO/l970 Primary Examiner-Ralph D. Blakeslee Allorney. Agent. or Firm-John M. May; W. H. MacAllister [57] ABSTRACT The present invention relates to data terminals for use in a TDMA communication system which provides the individual data terminals with synchronization error measurements and other commands. Each individual data terminal is capable of transmitting a narrowband coarse synchronization signal in response to a system command, thereby permitting rapid initial synchronization to be achieved. The disclosed data terminals transmit data in burst fashion at one uplink bandwidth, and receive downlink data at a second. narrower bandwidth.

2 Claims, 43 Drawing Figures Subseriber lines I IEIIIEE" 9.879.589

SHEEI l l 3F 2 5 Rate Frame 4-Phese DownIink 690 buff" synchronize! demodulator receiver I r 671 I Decoder User m T|m|ng and oontroI unit T inal Data/Coarse sync enable q (A: controller muimd) I Coarse sync srqnel J Coder A 660 630 620 7 I r f f r f l I I Rate UpIink 4/2-Ph838 Uplink 680 1 buffer formetter modulator transmitter Fl 6. 6- GENERAL DATA TERMINAL CONFIGURATION terminal FI G. 4. COAFISE SYNC SIGNAL Other dim terminele F G. I S TDMA COMMUNICATION SYSTEM FITENWH ZZ E i 7875,58C

Subscriber address (From SC call request memory) 2610 1 Call request Parallel-In] and clue I s o I illbwlpfl flddlfifl Shift register mmmmm (To interface i unit) LLoed Enable From call placement Enable u. min-t9 T signal transmission to user 3:5 Subscriber address received Enable ring pattern (From command decoder) transmission to SC To Voice circuit assigned I I Enable termin'on patter 'nk (From user call request detector) transmission to SC n i l nattar r line y Downlink clear enable SC termination of call t Uplink clear enable (From SC terminate memory) No 10: User answer Downlmk data circuit All controller (Fmm program enable output signals also go to call Timing Uplink um circuit Program enable mutton FIG. 2 SPACE CRAFT CALL MODE CONTROLLER 520 Racaive 57 Transmit antenna 500 4 phm antenna burst demod/bit 540 550 synchronizer r i Up|ink cflmmllnimion 4-phase Downlink receiver lmmlilor mod transmitter 510 21m I 60 burst demod 1 F l G. 5. S TDMA SPACECRAFT REPEATER From user interunit T'ZIii-frsnzzmrs 64 Decoded voice circuits User call termination command terminate command detector User call termina- 755 tion controller User call request Phone number Voice circuit assignment Lina busy User answer Subscriber address Circuits busy signal Call request Voice circuit commands Voice circuit cleared acknowledgements Line busy signal Ring signal Called party answer 64 Voice circuits FIG. 7 A DATA TERMINAL DIGITAL EQUIPMENT TEE SC cell mode controller User call mode controller Downlink data circuit memory Spacecraft terminate pattern detector SHEET 08 0F 26 Downlink L From domodulltod synohronizor NRZ bit mourn 50 From 4-phao domodulnor Torminol V address I Rooovorod 52.4 722 J Mbps 0* J 2 co d mman a decoder 710 f 123 J r Spocoaoft call roquon a I memory rm sync marmnanoo UpIink d timing 728 2- 112 r K I 2-- Roforonoo timing Initial synchronization I I oontrollor 754 H u u k sync J correction logic V Coon. sync Coomsync I "d g I 2' 02-pin. modulator i r U Ink data and v modulator unable FIG. 7B. DATA TERMINAL DIGITAL EQUIPMENT '".TEHICTA F.2219 5 3.879.580 SHEET 07 8F 26 Minor frame sync pulse l-Deta transfer enable g- Read terminal address 52.4 Mbps field downiink dock RM T f timing Read command word Raad command magnitude Reset Reset Data Data Data JD. word ehannel chum" timing timing numb.

Minor Minor frame 1 810 F'G. 8. DOWNLINKTIMING rom rama IS-Bit syehromzer) sulmqn I l-Out 52.4 Mbpe P." a

IS-Bit data (8 Bits) output Data transfer enable (From dov nlink 1 timing) Terminal 1' I address Read terminal $2: 3 detected Odd? (From dgfgcfor I'ld'l downlink timing) R FIG. 9. TERMINAL ADDRESS DETECTOR i IQHL hZ'MZL JUFJ SHEET 8 8 BF 2 6 Clear signals (From using circuitry) Initial all Cell interrogate Supplemental call Command decode 00 d Circuits busy Command (From termini word word Accept time slot number add! dam") decoder .323 0 Accept C.S. measurement V Accept F.S. measurement f 7 Accept F.S.M. meeeurement Reed command Accept subscriber word (From Jr 2 address downlink 1 timing) 000 A 1020 e a t j (V 7 Reed command O r magnitude J 9 m (From downlink timing) (8 Bits) Store 1010 mulememe:

6.8M. Data word F s M (From terminal (16 Bits) Commend address L magnitude F.S.M.M. detector) T.S.N.

Subscriber addreee Fl 6. I0. COMMAND DECODER Downlink timing Downlink date decode V a Enable 2 (From C.P.C.) mm Ring Rm detection Ring F Ring fl fl non-occurrence detection enable Fling (From U.C.M.C.) terminated Clock Data l (From terminal (output address detector) CMC -u n 0d z "or f Lil U. serce m econro 2420 mum mode C.P.C. Call placement controller OOWOIIO" Detector clear (From ueer call mode controller) RlNG PATTERN DETECTOR SHEET [E 3F 2 6 Uplinlt start of frame 3810 f 3820 ww I Enable 1 No tim'e slot evailab a (From Ham 1) Can Run Twoway link detection 7 delay Uplink encode logic Fine sync enable no. 2 m maintenance (From ll placement inhibit controller) I lnitial synchronization FIG. 3 8 FINE SYNC MAINTENANCE RESET DETECTOR From Call bit clear M Assignment bit clear controllers I I1 10 Clock Ser l t From interface E a: par zllel umt a register Serial data cell request Voice circuit assignment voiu circuit numb (To call mode controllers) Store Phone Clock enable (From formatter) numb" "B o 67.2 Mbps clodt m "l. 1120 Coarse sync xmit enable FIG. I I. USER CALL REQUEST DETECTOR (From initial synchronization Control Emu controller) loqlc 67.2 Mbps 0* Ram 1710 Narrowbend link Transmitter enable Coarse Sign. Bit 1, time slot 51 sync from reference ll Coarse sync signal timing 67.2 Mbpe clock Bit we, I Time slot 800 L 1720 Q I F I 7 COARSE SYNC GENERAT 20 Start Uplink Bit time of s m of f ame frame decoder pulse Uplink sync I (From sync correction logic) 1 {2010 I Slot time Slot 67.2 Mops clock l Clock s'ot timing numb. (From reference tlmmqI timing e (1 l 2020 I Decoded Bit times F I G. 2 0. UPLINK TIMING "HT Lu:

3 SHEET lUOF 26 Reference timing 0.8. Xmit Enable mm 0.8M. Rcvd.---

C.S. Meas. update F.S.M. Rcvd1 mama To y correction I T.S. AssI nad-- I as. u I I 9': Call interrogate command detected sync F.S.M. not received terminate (To call placement controller) Initial SC call Trlanamit enable 0 cal placement can controller and uplink formatted F l G. I 5 INITIAL SYNCHRONIZATION CONTROLLER Enable (From call placement Phone no. controller) n I To format'ber SC termination of call i ig' placement (From SC terminate memory) ""9 N Enable ring pattern detector User terminate command (From user terminate Terminate pattern commend detector) tranemit enable (To uplink Do formatter] m I Controller Downlink data circuit program enable I Uplink data circuit program Downlink ring pattern enable transmission ended (Ans) Line busy (To interface unit) User terminate of user ll be I cod I as mg 9 Downlink clear enable Timing l Uplink clear enable Note: All output signals 0 also to call placement 752 controller. F 2 2. USER CALL MODE CONTROLLER Circuit Voice fig il lment circuit mg:

1 b lt nurgber N F G. l 2 USER CALL REQUEST FORMAT SHEET s I User all SC ll'litil' all To Nd latches sc Call "2 momma Cleer User all l l I Z 1310 Terminal address detected T.S. Received SC supplemental all Fine sync measurement received User all request enable To interfece unit) Timing l: l v lnitial sync enable A No active time slots Fin. inhibit Widebend call request transmit enable (From F.S.M. reset logic) 3C Cell control signals c (From SC all mode User all control signals (From user all mode SC all request memory eeercli enable controller) lnitiel synchronization Circuits busy signal (To interface unit) control signals Time sync meintenana enable Upllnk Sync Repeal user cull SC Circuits busy Uplink encode enable 1 V Latch m 1300 Channel 1320 Enable "Digitel Channel number commute" Do k dwod (From downlink l y; timing) I (Write pulse) Enable Enable Store Control I l Time slot no. ff 0. Latch Digital Time slot no. mung 1 mmpognof Uplink encode (From SC enable 2 :2 requ)est (Write pulse) mor ' Time slot no. L 1310 Time slot number (From uplink timing) F I G. '3 CALL PLACEMENT CONTROLLER Wait for time slot Time slot eeeigned Supplemental call Wait "m mm mm mm W m mm 4 Wm m m m c Y n 1.... m N M UMrmm W a I m mm m a w m Wu I. mm t 0 mm m mm m w Wm mm a wwm we mm m mm mm nquen memory and fine sync maintenance FIG- 4. CALL PLACEMENTCONTROLLER SC cell requen not received (Clear latches) p-gygmazzasrs .878580 Terminate and not synchronized Wait for initial sychronization enable Enable and user call request Enable and Wait for initial SIC call interrogate lnterrogete Coarse sync command detected transmission enable Coarse sync transmitted Wait for coarse sync error urement Coarse sync error measurement detected Update sync with C.S.E. meas Wnc updated Time slot assigned T Fine sync measurement error not detected fine sync codes I Fine sync measurement received Sync updated F G. l 6. INITIAL SYNCHRONIZATION CONTROLLER SHEET In F I;

A Sm |e4o 2 of frame Bit time 1 decoder 32: of

Time slot 1 r 1820 f 1810 0eg'lllator end I Bl! Clock Slot H Slot "lll'l'lb'l no I clock source l 1830 Decoded bit timee 67.2 Mbp digital clock F l REFERENCE TIMING m Voice circuit line no.

Clock eneble Active $32? Serial-In] commend interface ClOdK Parallel put lt unit shm (To ueer cell mode placement H controller and to user cell cm; (Fro L 32 termination controller) user cell mode 10 controller) 7 Cleer (From user termination controller) F I G. 32. USER TERMINATE COMMAND DETECTOR (From cell placement Voice circuit line L (From Rem no. 2) of controller) Gating Downlink decode (From user cell Ofllblei 1 and 2 request detector (From Rem no. 2

cell bitl r 3710 1 s 1 c 2 Set 2 Terminate pulse Di I (From Sc Voice terminate u drum Line line 54 number indicator storage (To be r memory glyeered 3720 im' Line bit clear 6 unit) w l:: interface unit) J FIG. 3?. LINE TEFlMlNATlON MEMORY fi'ffEiHEL-KFRZZETS 59 SHEEI UN 26 Wait for user call mode enable Timing Enable Transmit Transmit line busy to nphommbu interface tuo so Termination r pattern detected Imlng I Enable uplink 1 transmission and downlink detection 0f ring "tam User termination and ring pattern detected Ring pattern detected on downlink and no user termination User Terminate ring pattern transmission Disable downlink decoding to SC and enable uplink voice encoding Timing Timing F' G. USER CALL MODE CONTROLLER STATE DIAGRAM TfTEIIYCQ-CEiFZGTS Q BYELSBO SHEET 19S? 26 Detected Timing Xmit Disable subscriber downlink address to decoding interface unit Timim Timing Disable uplink transmission Voice circuit wished Timing Transmit ring Terminate pattern to pattern detected spacecraft and wait for answer from user Enable downlink voice decoding Timing Terminate ring pattern transmission and enable uplink voice encoding Timing F l G. 2 7 SPACECRAFT CALL MODE CONTROLLER 

1. In a data terminal adapted for use in a time division multiple access communication system, the combination comprising: means for converting incoming user signals into respective digital words; means for multiplexing each of said digital words into respective time slot data at respective pre-assigned time slot times; means for transmitting said respective time slot data as a burst of data having a preamble comprising a data-free guard time interval, fixed digital data for permitting a processing repeater to acquire bit and word synchronization with said data burst, and variable digital call request data for use by said processing repeater, as an uplink burst transmission at a first given data rate during said pre-assigned time slot times; means for receiving, demodulating and maintaining synchronization with an essentially continuous downlink transmission free from said guard time intervals at a second data rate slower than said given data rate; means for identifying pre-assigned channels within said downlink transmission; means for demultiplexing data in each of said pre-assigned channels into a respective digital word; and means for converting said digital word into an outgoing user signal.
 1. In a data terminal adapted for use in a time division multiple access communication system, the combination comprising: means for converting incoming user signals into respective digital words; means for multiplexing each of said digital words into respective time slot data at respective pre-assigned time slot times; means for transmitting said respective time slot data as a burst of data having a preamble comprising a data-free guard time interval, fixed digital data for permitting a processing repeater to acquire bit and word synchronization with said data burst, and variable digital call request data for use by said processing repeater, as an uplink burst transmission at a first given data rate during said pre-assigned time slot times; means for receiving, demodulating and maintaining synchronization with an essentially continuous downlink transmission free from said guard time intervals at a second data rate slower than said given data rate; means for identifying pre-assigned channels within said downlink transmission; means for demultiplexing data in each of said pre-assigned channels into a respective digital word; and means for converting said digital word into an outgoing user signal. 